Vapor electric device



June 17, 1941 J. SLEPIAN VAPOR ELECTRIC DEVICE Filed Sept. 15, 1939 2 Sheets-Sheet l INVENTOR Joagofi SAP Dian.

WITNESSES: 0&0 7%.W

ATTORNEY June 17, 1941. s N 1 2,246,327

VAPOR ELECTRIC DEVICE Filed Sept. 15, 1939 2 Sheets-Sheet 2 WITNESSES: INVENTOR 05/0 7 L %/WL N Jose 0h S/ep/QN. 4 W v 1? A rm ATTORN EY boiler I.

- Patented June 17, 1941 VAPOR ELECTRIC nnvlcn Joseph Slepian, Pittsburgh, Pa., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application September 15, 1939, Serial No. 295,100

Claims.

My invention relates to ahigh vacuum pump and particularly to means for increasing the emciency of a mercury vapor vacuum pump.

It has long been known that the pumping efficiency of a mercury vapor pump is dependent upon the condensing efiiciency of the vapor condenser of the pump. It has recently been discovered that metallic condensing surfaces were subject to an'erratic change of condensing efiiciency, probably because of some poisoning of the condensing surface. I have discovered that this loss of condensing efficiency may be prevented by an ion bombardment of the condensing surface.

It is, accordingly, an object of my invention to provide a mercury vapor pump in which the condensing surface is maintained at a high efflciency by means of an ion bombardment of the condensing surface.

It is a further object of my invention to provide a high efiiciency mercury vapor pump.

Other objects and advantages will be apparent from the following detailed description taken in conjunction with the accompanying drawings,

in which: v I

Figure 1 is a schematic illustration of a-vapor pump according to my invention, and

Fig. 2 is a similar illustration of a modified pump according to my invention.

In the embodiment of my invention according to Fig. l, the pump comprises a suitable vaporizing chamber such as a mercury boiler I provided with a suitable heating element illustrated V as an electric resistance heater 2. The motive vapor produced in this vaporizing chamber I is passed through a conduit or passage 3 which terminates in a suitable nozzle 4 within a pumping chamber 5 to which is connected an inlet passage 3 from the device being evacuated. side walls 1 of this pumping chamber 5 are preferably constructed of material such as steel or iron, these side walls being cooled by any suitable device such as the cooling coil 8 arranged in intimate contact with the outer surface of the side walls 1. A suitable exhaust 9 for the non-condensible gases is arranged adjacent one end of the pumping chamber 5, connecting to the back-up pump (not shown). Pref rably a suitable conduit is provided for returning the condensed vapor to the vaporizing chamber or In order to increase and maintain the condensing capacity of the condensing surfaces 1, suitable metallic sections are provided in the vapor passage 3. Preferably, one of these me- The 'is so arranged that a glow discharge is maintained between the sections 4 and 10 with the cathode being on that section 4 immediately adjacent the'pumping chamber 5. The glow discharge provides a plurality of positive ions in the motive vapor, and in order to secure an ion' bombardment of the condensing surface 'I, a suitable source of potential I3 is connected between the cathode 4 and the condensing surface I, the condensing surface I being maintained at a nega tive potential with respect to the cathode section t.

The resulting ion bombardment maintains the condensing surface I in a state of high efficiency, probably by removing film of dirt or other impurities at or adjacent to the condensing surface -I.

The modification according to Fig. 2 is substantially similar to theprevious modification but the parts are constructed of metal so that it is adapted to more strenuous operation or in places where mechanical injury might result to a glass pump.

The boiler 20 is preferably provided with an internal heater 16 of high capacity while the boiler is of small Volume to secure faster heating than the conventional heater of Fig 1, while to accommodate the desirablevolume of mercury, the pump chamber 2! is extended to provide a reservoir 22.

The passage 23 for the motive vapor is constructed of metal and insulated from the pump chamber 2| by means of a suitable insulator herein shown as a glass seal 24. In order to secure the desired ionizing discharge, the passage 23 is divided into a plurality of sections by means of a suitable insulator 25.

The ionizing discharge is then maintained between the sections of the passage 23 by a suitable source of potential I2 and the side walls of the chamber 2| are maintained at a negative potential by means of the battery l3.

The operation of the pump is then as follows: The boiler is heated to produce motive vapor which flows through the passage to the nozzle 4 while an ionizing discharge is maintained in the ized mercury vapor flows through the nozzle entraining the gas from inlet 6 as is well known while the gas is discharged through passage 9. The pumping efliciency depends upon the condensing ability of the pump for the motive vapor. The negative potential applied to the condensing surface by the source l3 attracts the positive ions in the motive vapor securing an ion bombardment of the condensing surface. The ion bombardment for some reason not fully understood maintains the condensing ability of the surface at a high level so that the pump has a hight pumping speed and high efficiency.

For the purposes of illustration, I have shown and described certain specific embodiments of my invention.

It will be apparent that changes and modifications can be made therein without departing from the true spirit of my invention or the scope of the appended claims.

I claim as my invention:

1. A high vacuum pump comprising a boiler for producing motive vapor, a condensing chamber, a passage for conducting vapor from said boiler to said chamber, means for returning condensed material from said chamber to said boiler, means for producing a glow discharge in a portion of said passage and means for producing an ion bombardment of the condensing surfaces of said condensing chamber.

2. A high vacuum pump comprising a boiler for producing motive vapor, a condensing chamber, a passage for conducting vapor from said boiler to said chamber, said passage including a plurality of conducting sections insulated from each other, one of said sections being adjacent the condensing chamber, means for producing a glow discharge between said sections, means for impressing a negative potential on the walls of said condensing chamber and a conduit for returning condensed vapor to said boiler.

3. A mercury vapor pump comprising a boiler, a condensing chamber, a vapor passage between said boiler and said condensing chamber, a mersage, means in said passage for ionizing the vapor and means-tor applying a negative potential to the walls of the condensing chamber to secure an ion bombardment of said walls.

4. A mercury vapor vacuum pump comprising a vapor generating chamber, a vapor condensing chamber, a vapor passage interconnecting said chambers, a return connection for returning condensed mercury from the condensing chamber to the generating chamber, insulating means between the generating chamber and the condensing chamber, a further insulating means in said vapor passage to provide two sections, means for producing a glow discharge between said sections and means for impressing a negative potential on the walls of "the condensing chamber,

5. A high vacuum pump comprising a boiler for generating motive vapor, a pumping chamber, a vapor passage between said boiler and said chamber, said passage extending into the pumping chamber, an inlet opening in said chamber adjacent said passage, a cooled metallic condensing surface in said chamber, an exhaust part in said chamber, insulated metallic portions in said vapor passage, one of said portions being adjacent said chamber, a source of potential connected between said metallic portions to produce a glow discharge therebetween with that portion nearest the chamber active as a cathode, a second source of potential connected between said portions and the condensing surface to maintain said surface at a negative potential with respect to said portions.

JOSEPH SLEPIAN. 

